The invention is directed to filamentary reinforced composite rings and methods of making these rings.
The present method of making reinforced rings e.g., torus-shaped or doughnut-shaped, is to first make a unidirectional monolayer strip or tape having a width equal to the maximum height of the desired rings. The strip is rolled into a ring having a desired inside and outside diameter. The thus-formed ring is then consolidated using either internal or external radial pressure, that is, pressure normal to the strip surface. Lug reinforcements have been made by a method similar to the method used to make these rings. Unless the strip or tape is continuous, there is no filament continuity across the thickness of the ring.
Localized circular reinforcement of attachment holes are not and cannot be made by rolling strips into rings. Typically, these localized circular reinforcements are made by cross-plying (0.degree.,.+-.45.degree.) the unidirectional laminate. Another way of making a ring having a rectangular cross-section would be to wind a plurality of layers of filaments on a mandrel where each layer is separated by a sheet of matrix material. The winding progresses until the desired thickness is achieved. The winding is then removed from the mandrel and consolidated.
Applicants know of no prior art patents or articles which are closely relevant to the process and structure embodied in the present invention. However, several prior art forms that may be useful to form rings or toruses are described in U. S. Pat. Nos. 3,427,185; 3,575,783; 3,900,150; 3,984,043; and 3,991,928.